Injection molding of plastic parts using cold runner and hot runner systems is known. Several devices and techniques have been used to remove the plastic parts from the molds using stripper plates and ejectors when the molded has a geometry that allows the ejection from the core or cavity along a single axis that corresponds to the direction of opening and closing the cavity via the movements of the mold plates coupled to the injection molding machine platens.
Reference is made in this regard to U.S. Pat. Nos. 3,905,740, 5,865,241, and 7,234,930 and to WO Patent Publication No. 2012/045173.
Unlike in the above mentioned references, there are applications in the injection molding industry where the shape of the molded part is not axially symmetrical and has different portions arranged under an angle that have a hollow shape. This requires a special design of the mold cavity and a need to have cooling cores arranged at different angles relative to a main axis defined by the opening and closing of the mold to allow the final molded part to be cooled and ejected from the mold cores.
These molded parts may have in some applications a body having at least two interconnected segments where the segments are hollow and each segment has an axis, the axis of one segment being angled with respect to the axis of the other segment.
To properly mold such a part having angled hollow parts the cooling circuits of the cores and cavities need to be specially designed to meet both the cooling requirements and the constraints of the mold design, especially when there is a need for high cavity molds having a tight pitch between the mold cores and cavities.
Such molded parts are often needed for medical devices and such parts need to be molded not only accurately but also in large quantities and in a short period of time. This translates in the need to have accurate molds having a large number of mold cavities and a relative short cycle time.
These parts can be molded using both cold runner molds and hot runner molds. In the event a hot runner mold is selected, the hot runner system includes a manifold and several hot runner nozzles that can be either valve gated or thermal gated.
In the event where a hot runner system having movable valve pins is needed to mold these parts, the spacing on the mold side is rather limited and the cooling elements and cooling conduits need to be adapted and further improved to meet the quality requirements of the parts and the productivity demands.
There is a need to further improve the cooling of the cores when they are surrounded by a movable stripper plate having cooling channels.